Recent evidence has refuted claims that special perceptual phenomena, such as categorical perception, selective adaptation, and right ear advantages, are unique to phonetic perception. Special, low level auditory mechanisms, however, still might handle acoustic cues for speech. This project will analyse how rise time of the amplitude modulation function signals two apparently similar perceptual distinctions: the linguistic one between affricates and fricatives and the musical one between plucked and bowed sounds from stringed instruments. Synthetic musical and speech stimuli will be used in experiment with identification, discrimination, and selective adaptation paradigms. Initial studies will attempt to reconfirm that categorical perception occurs in both the linguistic and the musical cases. Succeeding experiments with musical and speech stimuli will examine the role of spectral as against temporal cues in perception of rise time. Preliminary findings suggest that the cues are temporal. If these results prove correct, further experiments will try to define the nature of the temporal cues. Dichotic adaptation studies will be done to see whether central mechanisms which receive binaural inputs contribute to processing of rise time information from both the linguistic and musical stimuli. Finally, the effect of carrier spectrum on the distinction between plucked and bowed sounds will be investigated. These studies will assess the spectral "tuning" of perceptual mechanisms sensitive to rise time. The project should provide evidence on whether similar linguistic and musical distinctions which depend on rise time actually use common auditory mechanisms.